biochem Flashcards
Water forms Hydrogen Bonds with?
Sulfur, oxygen and nitrogen atom (SON)
Define amphoteric and amphipathic
Amphoteric - acts as both an acid and a base, Amphipathic - has hydrophilic an hydrophobic parts
What is the normal pH?
7.35 - 7.45
DKA Criteria
Diabetic, Ketosis (+) urine ketones, ABG that documents acidosis
Important physiologic buffers
Bicarbonate - extracellular, Proteins - intracellular
Distinct versions of a given enzyme that catalyze the same reactions
Isozymes
Enzymes that catalyze the joining together of 2 molecules coupled to the hydrolysis of ATP
Ligases
Refers to the enzyme and its co-factor
Holoenzyme
True or false: enzymes that follow the Michaelis-Menten equation have a hyperbolic curve
True - equation describes how reaction velocity varies with substrate concentration
Reversal of competitive and non competitive inhibitors
Competitive - increase substrate, Noncompetitive - increase enzyme
Vmax change during inhibition
Competitive - not changed, Non competitive- lowered
What enzyme markers would best confirm a re-infarct?
CK-MB
Can be used to predict whether a reaction is spontaneous or not
Change in free energy
Equation of Change in Free Energy
Energy currency of the cell. It’s hydrolysis yields a large
ATP,
Differentiate oxygen phosphorylation from substrate level phosphorylation
Oxidative phosphorylation - mitochondria, oxygen needed. Substrate level phosphorylation - cytoplasm and mitochondria, oxygen not needed
Where does the ETC occur?
Inner mitochondrial membrane
2 electron carriers in the ETC
NAD+ from Vit B3 (thiacin), FAD from Vit B2 (riboflavin)
Only non-protein part of the ETC
Coenzyme Q - lipid, ubiquinone
Final electron acceptor in ETC
Oxygen
Protons re enter the mitochondrial matrix in ETC through?
Complex V - results in synthesis of ATP, contains ATP Synthase
2 components of ATP Synthase
F0 - channel where protons pass through, F1 - generates ATP from ADP and Pi
Names of the complexes in the ETC
I-NADH dehydrogenase, II-Succinate dehydrogenase, III-Ubiquinol, IV-Cytochrome oxidase
ETC inhibitor: Dimercaprol
Complex III - antidote to lead poisoning
ETC inhibitors: Barbiturates
Complex I
ETC inhibitors: cyanide
Complex IV
ETC inhibitors: carbon monoxide
Complex IV
ETC inhibitors: malonate
Complex II
Antidote to cyanide poisoning (bitter almond breath)
Amyl nitrite
Neonates rely on this protein to produce heat and prevent hypothermia
Thermogenin - through uncoupling
Macrolide that acts as an ATP Synthase inhibitor
Oligomycin
3 reactive oxygen species
Superoxide (O2), hydrogen peroxide (H2O2), and hydroxyl radical (OH)
Defenses against ROS accumulation
Catalase, Peroxidase, Superoxide dismutase
Glucose + Glucose
Maltose
Glucose + Galactose
Lactose
Glucose + Fructose
Sucrose
Mitochondrial disease affecting complex I
MELAS - mitochondrial encephalopthy, lactic acidosis, stroke like episodes
Mitochondrial disease affecting complex III
Leber’s hereditary optic neuropathy
Sugar units (disaccharides) are linked by?
Glycosidic bonds
Differentiate a proteoglycan from a glycoprotein
Proteoglycan (carbs>proteins), Glycoprotein (protein>carbs)
Polysaccharide found in cereals, potatoes, nuts
Starch
Polysaccharide of fructose, can be used to check renal function
Inulin
Compounds that have the same chemical formula but different structures
Isomers
Compounds that differ in configuration around only one specific carbon atom
Epimers
Sugar form that is more common in enantiomers
D-sugar
2 forms of anomers
Fischer projection (linear), and Haworth projection (ring)
Enzyme that can hydrolyze complex carbohydrates to disaccharides
Pancreatic amylase
Predominant transporter of glucose and galactose
SGLT 1 - via secondary active transport
Transporter for glucose, galactose and fructose
GLUT 5 - via facilitated diffusion
Transporter for all sugars
GLUT 2 - via facilitated diffusion
2nd messenger of insulin
Tyrosine kinase
Protein kinase G acts on what pathway?
cGMP
Substrate used in the inositol triphosphate system
Phosphatidylinositol
Enzyme that converts ATP to cAMP
Adenylate cyclase
Enzyme that degrades cAMP to 5 AMP
cAMP phosphodiesterase
GLUT transporter whose function is insulin stimulated uptake of glucose
GLUT 4 - found in muscle and adipose tissue
GLUT transported whose function is absorption of glucose in the lumen
GLUT 5 - in the small intestine
Where does glycolysis occur?
Cytoplasm of all cells
Rate limiting step of Glycolysis
Fructose 6 phosphate ? fructose 1,6 bisphosphate (E: PFK 1)
End products of anaerobic and aerobic glycolysis
Lactate (anaerobic), Pyruvate (aerobic)
Isozymes that catalyze the phosphorylation of glucose
Hexokinase, Glucokinase
Allosteric activator of PFK 1
PFK 2
Enzyme that catalyzes the formation of pyruvate
Pyruvate kinase
Malate aspartate shuttle is found in the?
Liver, kidney and heart (1 NADH = 3ATP)
Glycerol phosphate shuttle is found in the?
Skeletal muscle and brain (1NADH = 2 ATP)
What organs convert pyruvate to lactate?
RBCs, lens and cornea of eye, kidney medulla, testes, WBC
Most common enzyme defect in glycolysis?
Pyruvate Kinase Deficiency - presentation is chronic hemolytic anemia
Central molecule from pyruvate that enters the Kreb’s Cycle
Acetyl CoA
Congenital lactic acidosis. X linked dominant disease
Pyruvate dehydrogenase deficiency - treat with a ketogenic diet
Final common pathway for the aerobic oxidation of all nutrients
TCA/Kreb’s Cycle/Citric Acid Cycle
Rate limiting step in the Kreb’s Cycle
Isocitrate ? alpha ketoglutarate (E: isocitrate dehydrogenase)
Fluoroacetate (rat poison) inhibits what step in the Kreb’s Cycle?
Citrate ? Isocitrate (E: Aconitase)
Arsenite inhibits what step in the Kreb’s Cycle?
Alpha ketoglutarate ? Succinyl CoA (E: alpha ketoglutarate dehydrogenase)
Where does gluconeogenesis occur?
90 % liver, 10% kidney
Rate limiting step in Gluconeogenesis
Fructose 1,6 bisphosphate ? Fructose 6 phosphate (E: fructose 1,6 bisphosphatase)
Cycle that converts lactate to glucose via hepatic gluconeogenesis
Cori cycle - energy expense of 4 ATPs
Carboxylases require this as a co-factor
Biotin
Rate limiting step in the Cori Cycle
Fructose 1,6 bisphosphate ? fructose 6 phosphate (E: fructose 1, 6 bisphosphatase)
What are the dual functions of fructose 2,6 bisphosphate
Promotes glycolysis and inhibits gluconeogenesis
What enzyme does muscle lack to produce glucose?
Glucose 6 phosphatase
Blood concentration of glucose resulting to glucosuria
> 180mg/dL